Isopsephy

Isopsephy (/ˈaɪsəpˌsɛfi/; isos meaning "equal" and psephos meaning "pebble") is the Greek word for the practice of adding up the number values of the letters in a word to form a single number. Isopsephism, the occurrence of isopsephy, is frequently used as a synonym. The early Greeks used pebbles arranged in patterns to learn arithmetic and geometry.

Isopsephy is related to gematria, the same practice using the Hebrew alphabet, and the ancient number systems of many other peoples (for the Arabic alphabet version, see Abjad numerals). A gematria of Latin-script languages was also popular in Europe from the Middle Ages to the Renaissance and its legacy remains in numerology and Masonic symbolism today (see arithmancy).

Until Arabic numerals were adopted and adapted from Indian numerals in the 8th and 9th century AD, and promoted in Europe by Fibonacci of Pisa with his 1202 book Liber Abaci, numerals were predominantly alphabetical. For instance in Ancient Greece, Greek numerals used the alphabet. It is just a short step from using letters of the alphabet in everyday arithmetic and mathematics to seeing numbers in words, and to writing with an awareness of the numerical dimension of words.

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